Cerebral oximetry during infant cardiac surgery: evaluation and relationship to early postoperative outcome.

Background: We examined changes in cerebral oxygen saturation during infant heart surgery and its relationship to anatomic diagnosis and early outcome.

Methods: Regional cerebral oxygen saturation (rSO(2)) was measured by near-infrared spectroscopy in 104 infants undergoing biventricular repair without aortic arch obstruction as part of a randomized trial of hemodilution to a hematocrit of 25% vs 35%.

Results: Before cardiopulmonary bypass (CPB), infants with tetralogy of Fallot had higher rSO(2) values compared to those with D-transposition of the great arteries (D-TGA) or ventricular septal defect (P < 0.001). During CPB cooling, low flow, and at the termination of CPB, D-TGA subjects had the highest rSO(2) values (P < 0.001). There were no significant associations between intraoperative rSO(2) and early postoperative outcomes after adjustment for diagnosis. In 39 D-TGA subjects with > or =5 min of deep hypothermic circulatory arrest (DHCA), there was no correlation between the rSO(2) (91% +/- 6%) or hematocrit (29.2% +/- 5.5%) at the onset of arrest and the rate of decline in rSO(2) during arrest.

Conclusions: Intraoperative rSO(2) varies according to anatomic diagnosis but accounts for very little of the variance in early outcome. As measured by frontal near-infrared spectroscopy, higher levels of hematocrit and current perfusion techniques appear to provide an adequate oxygen reservoir prior to relatively short periods of DHCA.